In the micro-fluidic field there is known a type of system comprising a channel, which includes two segments connected to one another by a valve. The valve usually includes a partition arranged along the channel to separate the two segments and a membrane of an elastomeric material connected to a wall of the channel in the area of two holes, each of which is arranged at an end of a respective segment in the area of the partition. The valve further comprises a pneumatic actuator, which is adapted: on one side, to create a depression so as to deform the valve and, therefore, connect the two segments of the channel; on the other side, to exert a pressure to push the membrane against the wall of the channel so as to close the two holes and isolate the two segments.
Known valves and circuits of the above indicated type are for example disclosed in WO2008115626 (see in particular FIG. 2) and in WO2004061085 (see in particular FIGS. 1A-1E). It should be noted that WO2004061085 discloses only one element made of elastomeric material (indicated by numerals 11 and 157 in FIGS. 1B-1E).
The paper by the title “Smallest dead volume microvalves for integrated chemical analyzing systems” (ISBN: 978-0-87942-585-2) discloses a valve with a single photoresist membrane.
The valves of the state of the art have considerable disadvantages.
A first series of drawbacks results from the fact that the preparation of this kind of valves is often complex. In particular, it should be noted that it is often necessary (although difficult) to selectively connect the membrane to the wall of the channel and not to the partition. Drawbacks are also associated to the complexity of producing several parts of the micro-fluidic system independently of one another.
Furthermore, valves of the above disclosed type are often relatively bulky and may not be incorporated in complex microfluidic circuits, but instead must be arranged externally and connected to microfluidic circuits by means of relatively long channels.